A lawyer, Aiko, and a veterinarian, Kai, meet while walking their dogs, which are instantly drawn to each other. Meanwhile, a Korean chaebol heir, Seo-ha, arrives in Japan with a purpose.

Seo-ha claims Kai's dog is his, and Aiko, as a lawyer, tries to find a legal way for Kai to keep the dog. To gain her trust, Seo-ha takes Aiko on a date in Yokohama.

Kai's dog is suddenly kidnapped. He suspects Seo-ha, who denies any involvement. Aiko reveals to Kai that they share a past connection involving a stray dog from their childhood.

Kai reluctantly agrees to live with Seo-ha. At work, Aiko finds herself in a difficult position, forced to legally oppose Kai over the ownership of his dog due to her boss's decision.

An old friend returns with a shocking offer for Kai, bringing back a dark past. Tasked to investigate Seo-ha, Aiko instead learns Kai's secrets.

Aiko's confession leaves Kai confused. A new rival emerges as Seo-ha’s sister arrives, confesses to Kai, and vets Seo-ha for the family succession.

Aiko is bewildered after Seo-ha confesses his feelings for her. Aiko's mother, who is consulting her about a divorce, invites both Kai and Seo-ha to dinner, leading to a tense meal.

After Aiko's impulsive kiss with Kai, things are awkward. Seo-ha selflessly pushes them closer. As they finally discuss the kiss, a crisis hits Kai.

Guilt-ridden over Kai's crisis, Seo-ha flees to Korea and rejects their pleas. Aiko's subsequent attempt to uncover the truth backfires, putting her own career in jeopardy.

Seo-ha returns with evidence, uniting the trio for a final battle. As he plans to propose to Aiko, Kai makes the heartbreaking choice to support his friend over his own feelings.